First experiences with alcohol in humans occur predominantly in adolescence, and drinking in a context of social interactions appears to be a virtually universal situation. Attractiveness of ethanol at this age is predominantly based on its properties to produce social facilitation and alleviate anxiety, since a high significance of social interactions, high social motivation and high frequency of anxiogenic situations characterize adolescence as a developmental period. Age-specific neural alterations also make adolescents notably hyposensitive to a number of the effects of ethanol. Therefore, the high risk of extensive alcohol use in adolescence is determined by a unique combination of social, motivational, environmental and neurobehavioral factors. Given that certain behavioral features, including age-related increase in social behavior, are common among adolescents of different mammalian species, peer-directed social activity of adolescent rats appears to have promise as an experimental model for the study of adolescent responsiveness to ethanol. The present proposal is to investigate how social and environmental factors contribute to responsiveness to ethanol in adolescence. Specifically, the proposed experiments will explore acute effects of ethanol on different forms of social behavior and social motivation in familiar and unfamiliar (anxiogenic) environments. Testing in a familiar environment will assess age-related differences in sensitivity of social behavior to activating and suppressing effects of ethanol, whereas testing in an unfamiliar environment will provide information about age-related differences in sensitivity to the anxiolytic effects of ethanol. Given that responsiveness to ethanol can be modified dramatically by repeated administrations, and that the emergence of these adaptations may also vary with age, the proposed experiments will investigate age-related peculiarities in the development of chronic tolerance to inhibitory effects of ethanol on social behavior as well as to its anxiolytic effects. Comparison of ethanol effects in weanling, adolescent and adult rats will allow us to outline peculiarities of adolescent responding to ethanol that may be unique to adolescence as a developmental period.